Various surgical techniques may be used to repair a diseased or damaged heart valve, such as annuloplasty (contracting the valve annulus), quadrangular resection (narrowing the valve leaflets), commissurotomy (cutting the valve commissures to separate the valve leaflets), or decalcification of valve and annulus tissue. Alternatively, the diseased heart valve may be replaced by a prosthetic valve. Where replacement of a heart valve is indicated, the dysfunctional valve is typically removed and replaced with either a mechanical or tissue valve. Tissue valves are generally preferred over mechanical valves because they typically do not require long-term treatment with anticoagulants.
A number of different strategies have been used to repair or replace a defective heart valve. Open-heart valve repair or replacement surgery is a long and tedious procedure and involves a gross thoracotomy, usually in the form of a median sternotomy. In this procedure, a saw or other cutting instrument is used to cut the sternum longitudinally and the opposing halves of the anterior or ventral portion of the rib cage are spread apart. A large opening into the thoracic cavity is thus created, through which the surgeon may directly visualize and operate upon the heart and other thoracic contents. The patient must be placed on cardiopulmonary bypass for the duration of the surgery.
Open-chest valve replacement surgery has the benefit of permitting the direct implantation of the replacement valve at its intended site. This method, however, is highly invasive and often results in significant trauma, risk of complications, as well as extended hospitalization and painful recovery period for the patient.
Minimally invasive percutaneous valve replacement procedures have emerged as an alternative to open-chest surgery. Unlike open-heart procedures, this procedure is indirect and involves intravascular catheterization from a femoral vessel to the heart. Because the minimally invasive approach requires only a small incision, it allows for a faster recovery for the patient with less pain and the promise of less bodily trauma. This, in turn, reduces the medical costs and the overall disruption to the life of the patient.
The use of a minimally invasive approach, however, introduces new complexities to surgery. An inherent difficulty in the minimally invasive percutaneous approach is the limited space that is available within the vasculature. Unlike open heart surgery, minimally invasive heart surgery offers a surgical field that is only as large as the diameter of a blood vessel. Consequently, the introduction of tools and prosthetic devices becomes a great deal more complicated. The device must be dimensioned and configured to permit it to be introduced into the vasculature, maneuvered therethrough, and positioned at a desired location. This may involve passage through significant convolutions at some distance from the initial point of introduction.
Accordingly, while heart valve surgery produces beneficial results for many patients, numerous others who might benefit from such surgery are either unable or unwilling to undergo the trauma and risks of current techniques. Therefore, what is needed are methods and devices for performing heart valve repair or replacement, as well as other procedures within the heart and great vessels of the heart, that provide greater access to the heart valves than the currently minimally invasive techniques, while at the same time reducing the trauma, risks, recovery time and pain that accompany the more invasive techniques.
To this end, methods and systems for performing cardiovascular surgery by accessing the heart or great vessels through the apical area of the heart are disclosed in co-pending patent application Ser. No. 10/831,770, filed Apr. 23, 2004, which is incorporated herein by reference. The unique anatomical structure of the apical area permits the introduction of various surgical devices and tools into the heart without significant disruption of the natural mechanical and electrical heart function.
While access to the heart through the femoral vessels in the conventional percutaneous methods are limited to the diameter of the smallest vessel through which it must pass through (typically about 8 mm), access to the heart through the apical area permits a significantly larger and more direct working space (up to approximately 25 mm). By directly access into the heart and great vessels through the apex, there is greater flexibility as to the type, size and capacity of surgical devices to perform valve replacement or repair surgery.
In any valve repair or replacement surgery, however, manipulation of the heavily calcified valves may result in dislodgment of calcium and valve or other surrounding tissue and debris, with subsequent embolization and blockage. Accordingly, there is a risk that embolic material will be dislodged by the procedure and will migrate through the circulatory system and cause clots and strokes. A need therefore exists for safely containing embolic material during cardiovascular surgery.
Various systems and techniques have been proposed for removing debris from the circulatory system in order to prevent the debris from causing any harm. One technique involves temporarily obstructing the artery and then suctioning embolic material, debris and blood from the treatment site. This technique, however, requires that blood flow through the artery be obstructed, causing complete cessation or at least a substantial reduction in blood flow volume during a period of time which can be significant for organ survival. Another technique involves cutting the embolic material into small pieces such that they will not occlude vessels within the vasculature. With this technique, however, it is often difficult to control the size of the fragments which are severed and larger fragments may be severed accidentally.
Thus, there is a need for an apparatus and method for capturing debris that is dislodged during valve repair or replacement surgery which substantially reduces the risk of embolic material escaping to the vessel and causing a blockage at a downstream location. There is also a need for an apparatus and method that can be introduced through the apical area of the patient's heart and positioned in a location downstream from and distal to the area in which the valve repair or replacement surgery is to be performed.